Fumarase is involved in DNA double-strand break resection through a functional interaction with Sae2

Area of Science:

• Molecular Biology
• Cell Biology
• Biochemistry

Background:

• DNA double-strand breaks (DSBs) are severe DNA damage forms.
• Improper DSB repair can lead to mutations, chromosomal rearrangements, and cancer.
• Homologous recombination (HR) and non-homologous end joining (NHEJ) are primary eukaryotic DSB repair pathways.
• Fumarase, a mitochondrial enzyme, is also found in the cytosol and participates in DNA damage response.

Purpose of the Study:

• To investigate the role of cytosolic fumarase in the homologous recombination (HR) DNA repair pathway.
• To determine if cytosolic fumarase interacts with Sae2 and influences DSB resection.

Main Methods:

• Depletion of cytosolic fumarase in yeast.
• Assessing the kinetics of HR repair and Mre11 localization at DSBs.
• Investigating the functional and physical interaction between fumarase and Sae2.
• Analyzing the impact of fumarase and Sae2 on DSB resection.

Main Results:

• Depletion of cytosolic fumarase in yeast delayed HR repair kinetics and prolonged Mre11 presence at DSBs.
• Overexpression of Sae2 mitigated the DSB sensitivity in fumarase-depleted yeast, indicating functional interaction.
• Cytosolic fumarase depletion inhibited DSB resection, while its overexpression or Sae2 overexpression restored resection.
• Cytosolic fumarase depletion reduced Sae2 cellular levels, suggesting fumarase regulates Sae2.

Conclusions:

• Cytosolic fumarase is essential for efficient homologous recombination repair of DNA double-strand breaks.
• Cytosolic fumarase regulates the DSB resection process, partly by controlling Sae2 levels.
• Fumarase and Sae2 functionally and physically interact in vivo, highlighting a novel role for fumarase in DNA repair.